CROSS-LINKING REACTIONS OF GELATIN FILMS

The cross-linking reaction was followed by measuring the horizontal and vertical swelling (water absorption) of the layers. It was found that the cross-linking of the gelatin with hardener could be adequately described as a pseudo-first-order reaction: E(H), Q = a + b* e(-kt) where E(H) - horizontal swelling Q - vertical swelling a - swelling after full hardening b - variable component of the swelling k - rate constant t - time Various influences on the size of the rate constant are described: gelatin concentration concentration of anionic wetting agents molecular weight distribution of the gelatin surface temperature of the film point of time addition of the hardener type of hardener The gelatin films were coated on production coaters with reproducible parameters of chilling and drying.